Polypeptide having protease activity, or protease, is a type of enzyme that hydrolyses peptide bonds in proteins. Protease is widely existed in animals, plants and microorganisms.
To date, more than one hundred of commercial proteases are on the market. Due to limited resources of using animals and plants, industrial protease production is mainly from extraction and preparation from bacillus subtilis, yeast, mold, Escherichia coli and other microorganisms. With in-depth researches on protease, industrial application of proteases has attracted more and more attention. At present, protease has been widely applied in fur, leather, silk, medicine, food, brewing, oil drilling and other industrial fields. The use of proteases for hair-removal and softening in leather industry saves time and improves labor health conditions. Furthermore, protease can also be used for silk degumming, meat tendering, and wine clarification. Clinically, proteases are helpful for treatments of indigestion bronchitis, vasculitis and other symptoms for animals and humans. Moreover, detergents added with proteases can efficiently remove blood and protein on dirty clothes. In addition, proteases are widely used in biochemical and molecular research experiments as a scalpel for proteins, which is indispensable to life science research.
Deinococcus radiodurans is an extremophilic bacterium, and is famous for its extremely strong resistance to ionizing radiation, ultraviolet ray, drying, and oxidative stress. Its extreme resistance is partly due to the gene pprI (gene name: dr_0167; GeneID: 1798483), a global regulator for DNA damage response and repair pathways. The gene product PprI (NCBI-GI: 15805204) is composed of 328 amino acids and is comprised of three functional domains: a zinc peptidase-like domain, a helix-turn-helix domain, and a GAF domain. The PprI protein possesses high specificity, strong heat resistance and elevated digestion efficiency, provides an ideal tool for basic scientific research and industrial application. Hence, the use of PprI as protease and the method for increasing its protease activity are especially desirable.